Method for insertion of an endoscope into the colon

ABSTRACT

A method for inserting an endoscope into the colon of a patient includes providing a generally rigid insert having proximal and distal ends and having a curved channel passing therethrough with a lateral opening at the distal end. The insert is inserted into the patient&#39;s rectum so that the distal end is in proximity to the sigmoid flexure of the colon. The endoscope is then passed through the channel and into the sigmoid colon.

This is a Divisional Application of Ser. No. 09/530,717, now U.S. Pat.No. 6,447,444, filed on Jul. 31, 2000, which is the National Phase ofPCT/IL98/00529, filed on Nov. 2, 1998, and whose contents areincorporated in their entirety by reference.

FIELD OF THE INVENTION

The present invention relates generally to medical probes, andspecifically to endoscopes.

BACKGROUND OF THE INVENTION

Various types of endoscopes are known in the art for visual inspectionand diagnosis of the rectum and sigmoid of the large intestine. Rigidrectoscopes and sigmoidoscopes are most commonly used for this purpose,since they are durable, easy to use and relatively inexpensive.

To perform an examination using the rigid rectoscope (or sigmoidoscope),the physician first inserts a speculum through the anus. An obturator,having a blunt, rounded distal end, is fitted inside the speculum andprotrudes distally therefrom to ease the insertion. Once the speculum isin place, the physician withdraws the obturator and closes the proximalend of the speculum with a plug. A special telescope is fitted into theplug, which enables the physician to view the inside of the rectum andsigmoid at the distal end of the speculum, either by direct vision orusing a video camera coupled proximally to the telescope. In order toilluminate the area under view, a light source in an external console iscoupled proximally to the speculum by fiberoptics. Typically, the plugalso includes one or more working channels, which are used forirrigation, insufflation or insertion of surgical tools through thespeculum.

Various rectoscopes and sigmoidoscopes of this type are availablecommercially. For example, Karl Storz GmbH, of Tuttlingen, Germany,offers the model 24911S rectoscope, which may be used with a rod lenstelescope (for example, model 24946B) to view the rectum either underdirect view or using a Karl Storz Endovision video camera. Therectoscope and accessories are made from stainless steel to allowdisinfection and autoclaving between uses.

Rectoscopes and sigmoidoscopes having a disposable speculum andobturator are also available, such as the KleenSpec disposablesigmoidoscope produced by Welch Allyn Inc., of Skaneateles Falls, N.Y.The speculum and obturator are made of plastic. The speculum clips orscrews onto a multi-use handle, to which a light source, telescope,video camera and instruments may be attached.

Flexible sigmoidoscopes and colonoscopes are also known in the art. Mostsuch scopes include a fiberoptic bundle for conveying images from theirdistal end, within the intestine, to an eyepiece or video camera fixedto the proximal end. Some such scopes, such as the Pentax ES-3801 PVEVideo Sigmoidoscope, made by Asahi Optical Company of Tokyo, have a CCDdetector with an objective lens at its distal end. By comparison withrigid rectoscopes and sigmoidoscopes, however, flexible scopes arecostly, fragile and difficult to clean.

SUMMARY OF THE INVENTION

It is an object of some aspects of the present invention to provide animproved endoscope, and particularly an improved rectoscope.

It is an object of some aspects of the present invention to provide avideo rectoscope that gives improved visibility of anatomical featureswithin the rectum.

It is another object of some aspects of the present invention to providea rectoscope that is easy and convenient for medical personnel to use.

It is a further object of some aspects of the present invention toprovide a rectoscope including an easily-replaceable disposable portion,thus minimizing or eliminating the need for disinfection andsterilization between uses.

It is yet another object of some aspects of the present invention toprovide methods and apparatus that facilitate insertion of an endoscope,particularly a rectoscope or sigmoidoscope, into a body cavity.

It is still another object of some aspects of the present invention toprovide an improved steering mechanism for an endoscope.

In preferred embodiments of the present invention, a rectoscopecomprises an elongate, generally rigid insertion member having a videocamera head at its distal end. The insertion member and camera head arecovered by a disposable sheath, which includes a transparent distalportion, preferably including an optical window, covering the camerahead. The camera head includes an image detector array, preferably a CCDarray, as is known in the art, along with a light source forilluminating an area of the intestine viewed by the camera head and anobjective lens, which focuses an image of the area onto the array. Thesheath, which is preferably made of a biocompatible plastic material, isremoved and discarded after use. The rectoscope is used to examine andtreat areas of the colon of a patient, specifically the rectal andsigmoid portions of the colon.

By comparison with rigid rectoscopes and sigmoidoscopes known in theart, the present invention can provide substantially improved imagequality, because the video camera head is placed at the distal end ofthe rectoscope, near the area under view. The distal positioning of thecamera head enables the present rectoscope to achieve both highermagnification and a wider field of view than video rectoscopes andsigmoidoscopes known in the art, in which the camera head views theintestine through a telescope from the proximal end of the scope.

In preferred embodiments of the present invention, the sheath comprisesa narrowed, generally bluntly pointed tip, to ease insertion of therectoscope through the anus. The narrowed tip thus performs the functionof the obturator used in insertion of rectoscopes and sigmoidoscopesknown in the art. Elimination of the obturator relieves a physicianusing the rectoscope of unpleasant odors and possible exposure toinfection that are commonly associated with removal of the obturator.

In some preferred embodiments of the present invention, the optical axisof the camera head is angled relative to the longitudinal axis of theinsertion member, and the distal end of the sheath is likewise angled,thus defining the narrowed tip. Preferably, the sheath has a bulbousprotrusion at the tip, which further eases insertion of the rectoscopethrough the anus.

In one such preferred embodiment, a mirror is fixed to the bulbousprotrusion, which is shaped so that the mirror is positioned within thefield of view of the camera head and is oriented obliquely relative tothe optical axis thereof. An image of the inner wall of the rectum orsigmoid is reflected from the mirror and captured by the camera head.The mirror thus enables the physician to see an image from analternative view angle, which may be useful particularly in observingand controlling the movement of tools that the physician inserts intothe rectum using the rectoscope, as described below.

In other preferred embodiments of the present invention, the narrowedtip of the sheath is formed by a plurality of leaves, formed of aresilient material, which butt together tightly in a closedconfiguration to cover the transparent portion of the sheath and thecamera head. During insertion through the anus, the closed leavesprotect the transparent portion from fouling by fecal matter, lubricantsor other substances. After the rectoscope has been inserted, the leavesare drawn apart, preferably by pulling the sheath back proximally, so asto expose the transparent portion of the sheath and allow the camerahead to receive images of the area of the intestine under view.

In some preferred embodiments of the present invention, the sheathincludes one or more working channels, which may be used for suction,irrigation, insufflation, passage of surgical tools or other functionsknown in the art. The rectoscope includes a handle, to which the sheathis attached, preferably by a quick connect/disconnect fitting.Preferably, the handle includes user controls for regulating suchfunctions as suction, irrigation and insufflation through the workingchannels. Further preferably, one or more of the working channelsinclude a one-way valve, to prevent back-flow of fluid (gas or liquid)used in irrigation or insufflation through the channels.

Although rectoscopes in accordance with the present invention aredescribed herein as being generally rigid, in some preferred embodimentsthe insertion member may include a flexible, resilient longitudinalsection. This section allows the rectoscope to bend during insertioninto the rectum, to make the insertion easier and less painful for thepatient. Such bending is not possible using rigid endoscopes known inthe art, and it differs from the bending of flexible endoscopes, whichdo not have the rigidity to maintain a particular shape and requirecomplex steering mechanisms to control their angle and direction ofbend.

In one such preferred embodiment, the rectoscope sheath comprises one ormore flexible, longitudinally-disposed inflatable bladders, preferablyat least two such bladders disposed radially within the sheath ondifferent sides of the flexible section of the insertion member.Preferably, the bladders are placed on opposing sides of the sheath. Thebladders are connected by respective valves to a suitable pressuresource. When the pressure in one of the bladders is increased, thebladder lengthens, whereas when the pressure is decreased, the bladdertends to shorten. Thus, the bend angle of the sheath and of theinsertion member therein is controlled by varying the pressure in theone or more bladders.

In another preferred embodiment of the present invention, a generallyrigid rectal insert having a curved channel therethrough is insertedinto the rectum, up to the sigmoid flexure. The insert is turned withinthe rectum so that the exit from the channel at the sigmoid flexureopens into the intestine in a direction generally along the axis of thesigmoid. The rectoscope including the flexible section, as describedhereinabove, is then inserted through the channel and is forced by therigidity of the insert to bend toward the sigmoid axis. The combinationof the insert and rectoscope, in accordance with this preferredembodiment, thus allows endoscopic inspection of a portion of theintestine that can generally be reached only using a more costlyflexible endoscope. The rectal insert described herein can also be usedin conjunction with flexible endoscopes known in the art, making iteasier to pass the endoscope through the sigmoid and reducing pain andthe possibility of accidental perforation of the intestine.

Although preferred embodiments are described herein with reference toinspection and treatment of the rectum, and endoscopes in accordancewith such preferred embodiments are referred to herein generally asrectoscopes, it will be appreciated that such endoscopes may similarlybe adapted and applied to serve as sigmoidoscopes. The principles of thepresent invention may similarly be applied to produce rigid endoscopesfor insertion into other body cavities, such as the throat, the vagina,or any other cavity large enough to receive an endoscope having a videocamera head at its distal end, as described herein.

There is therefore provided, in accordance with a preferred embodimentof the present invention, a video endoscope, including:

-   -   a generally rigid, elongate insertion member, having distal and        proximal ends;    -   a video camera head fixed at the distal end of the insertion        member; and    -   a sheath, which fits over and covers the insertion member, the        sheath having a distal portion covering the video camera head,        at least a section of which distal portion is substantially        transparent.

Preferably, the camera head includes a detector array and an objectivelens, which forms an image on the detector array.

In a preferred embodiment, the camera head is inclined obliquelyrelative to a longitudinal axis of the insertion member.

Preferably, the camera head includes a light source, most preferablyincluding one or more LEDs.

Preferably, the substantially transparent section of the distal portionof the sheath includes an optical window.

Preferably, the distal portion of the sheath includes a narrowed tip,which facilitates insertion of the endoscope through the anus. Furtherpreferably, the narrowed tip includes a bulbous protrusion.

Alternatively or additionally, the narrowed tip includes two or moreleaves, which are closed during insertion through the anus and openapart after insertion to expose the transparent section of the distalportion of the sheath. Preferably, to open the leaves, the sheath isshifted in a proximal direction drawn relative to the insertion member.

Preferably, the sheath contains a working channel passing longitudinallytherealong. Further preferably, the sheath includes a one-way valvewithin the working channel, for preventing back-flow of fluidtherethrough.

Preferably, the endoscope includes a handle, fixed to the proximal endof the insertion member, and the handle includes user controls forcontrolling the passage of fluid through the working channel.

In a preferred embodiment, at least a longitudinal section of theinsertion member is flexible and resilient. Preferably, the sheathincludes an inflatable bladder disposed longitudinally within thesheath, such that inflation of the bladder causes its length to increaseso that the insertion member bends.

In another preferred embodiment, a mirror is fixed in a position distalto the camera head within a field of view thereof and oriented obliquelyrelative to an optical axis of the camera head, so that the camera headcaptures an image reflected from the mirror. Preferably, the imagereflected from the mirror includes an area of a physiological structurein which a surgical procedure is to be performed using the endoscope.

There is further provided, in accordance with a preferred embodiment ofthe present invention, a steering mechanism for an elongate medicalprobe, including at least one controllably inflatable element fixed tothe probe, such that a longitudinal dimension of the element changesresponsive to inflation thereof, thereby causing the probe to bend.

Preferably, the at least one inflatable element includes two elementsdisposed radially on different sides of the probe, so as to bend theprobe in different, respective directions. Further preferably, the twoelements include first and second elements on opposing sides of theprobe, such that the first element is inflated and the second element isdeflated so as to bend the probe toward the side on which the secondelement is fixed.

Preferably, the at least one inflatable element includes an expandablewall section on an outer surface thereof, which expands and contractsresponsive to changes in the inflation of the element.

Preferably, the mechanism includes a pressure source which iscontrollably applied to the inflatable element so as control the bendingof the probe.

In a preferred embodiment, the probe includes a generally rigidendoscope, having a flexible section which is bent by the mechanism,wherein the endoscope preferably includes a disposable sheath, whichincludes the at least one inflatable element.

There is moreover provided, in accordance with a preferred embodiment ofthe present invention, a generally rigid rectal insert, having a distalend which is inserted into the rectum of a patient, the insert having acurved channel therethrough through which an endoscope is inserted intothe sigmoid portion of the colon of a patient.

Preferably, the distal end of the insert is brought into proximity withthe patient's sigmoid flexure, and the channel is curved so as to openlaterally out of the distal end into the flexure. Further preferably,the insert is rotatable within the rectum so as to align the opening ofthe channel at the distal end thereof with the intestine.

There is also provided, in accordance with a preferred embodiment of thepresent invention, a method of endoscopic inspection, including:

-   -   providing an elongate, generally rigid insertion member having a        video camera head at a distal end of the member;    -   fitting a disposable sheath over the member, such that the        camera head is covered by a substantially transparent portion of        the sheath;    -   inserting the insertion member, covered by the sheath, into a        body cavity of a subject; and    -   receiving video images within the body cavity from the camera        head.

Preferably, fitting the sheath includes fitting a sheath having anarrowed tip, and inserting the member includes first inserting thenarrowed tip into the cavity.

In a preferred embodiment, the narrowed tip is opened after insertion toexpose the substantially transparent portion of the sheath covering thecamera head, wherein opening the narrowed tip preferably includesshifting at least a portion of the sheath in a proximal direction overthe insertion member so as to separate two or more leaves that meet toform the narrowed tip.

Preferably, receiving the video images includes illuminating the insideof the body cavity using a light source in the video camera head.

Further preferably, fitting the disposable sheath includes fitting asheath having at least one working channel passing therethrough. In apreferred embodiment, the body cavity is insufflated by passing apressurized fluid through the working channel.

In a preferred embodiment, providing the insertion member includesproviding a member at least a longitudinal portion of which is flexibleand resilient, and inserting the member includes flexing the flexible,resilient portion. Preferably, inserting the member includes insertingan insert into the body cavity having a curved channel therethrough, andpassing the member through the channel. Alternatively or additionally,flexing the flexible, resilient portion includes inflating an inflatablebladder disposed within the sheath so that the length of the bladderincreases, thereby bending the portion.

Preferably, inserting the insertion member includes inserting the memberthrough the anus of the subject, and receiving the images includesreceiving images within the rectum or, alternatively or additionally,receiving images within the sigmoid.

There is further provided, in accordance with a preferred embodiment ofthe present invention, a method for steering a medical probe, including:

-   -   fixing an inflatable element to the probe; and    -   controllably inflating the element so as to change the length        thereof, thus causing the probe to bend.

Preferably, fixing the inflatable element includes fixing a plurality ofelements on different sides of the probe, so that each element causesthe probe to bend in a different, respective direction.

In a preferred embodiment, the medical probe includes a generally rigidendoscope at least a section of which is flexible, and whereincontrollably inflating the element causes the flexible section of theendoscope to bend.

There is additionally provided, in accordance with a preferredembodiment of the present invention, a method for inserting an endoscopeinto the colon of a patient, including:

-   -   providing a generally rigid insert having proximal and distal        ends and having a curved channel passing therethrough with a        lateral opening at the distal end;    -   inserting the insert into the patient's rectum so that the        distal end is in proximity to the sigmoid flexure of the colon;        and    -   passing the endoscope through the channel and into the sigmoid        colon.

Preferably, the insert is rotated to align the opening at the distal endof the insert with the colon before passing the endoscope therethrough.

Preferably, passing the endoscope includes passing a flexible endoscopethrough the channel or, alternatively, passing a generally rigidendoscope including a flexible portion through the channel, such thatthe flexible portion is bent by the curve of the channel.

The present invention will be more fully understood from the followingdetailed description of the preferred embodiments thereof, takentogether with the drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, partly sectional illustration of a rectoscope, inaccordance with a preferred embodiment of the present invention;

FIG. 2 is a sectional, detail view of a distal portion of the rectoscopeof FIG. 1;

FIGS. 3A and 3B are schematic, sectional illustrations of a rectoscopecovered by a sheath in closed and open configurations thereof,respectively, in accordance with another preferred embodiment of thepresent invention;

FIG. 4A is a schematic, sectional view of the distal portion of arectoscope, in accordance with another preferred embodiment of thepresent invention;

FIG. 4B is a schematic illustration of a video image captured by therectoscope of FIG. 4A;

FIG. 5A is a schematic, sectional view of the distal portion of arectoscope, in accordance with a preferred embodiment of the presentinvention;

FIG. 5B is a schematic, sectional illustration of a rectal insert,useful particularly in conjunction with the rectoscope of FIG. 5A, inaccordance with a preferred embodiment of the present invention; and

FIG. 6 is a schematic, sectional illustration of a rectoscope, inaccordance with still another preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is now made to FIG. 1, which is a schematic, partly sectionalillustration of a video rectoscope 20, in accordance with a preferredembodiment of the present invention. Rectoscope 20 comprises aninsertion section 22, which is inserted into the rectum of a subject,and a handle 24, which is grasped by a physician making the examination.Insertion section 22 includes an insertion member 28, fixed to handle24, and a disposable sheath 26, covering the insertion member. Member 28includes a video camera head 30 at the member's distal end, connected bywires 32 to handle 24. Preferably, sheath 26 comprises a biocompatibleplastic material, such as polycarbonate, and is attached to handle 24using a quick-connect fitting, as is known in the art. After use, sheath26 is removed and disposed of.

FIG. 2 is a schematic, sectional illustration showing details of thedistal end of insertion section 22, including camera head 30. The camerahead comprises a detector array chip 46, preferably comprising a colorCCD array 50, such as a Sony ICX087AKB CCD chip, with a suitable opticalfilter 48 affixed thereto. One or more lamps 42 illuminate an area ofthe intestine under view by the camera head. An image of the area isreceived through an optical window 36 in sheath 26 and focused ontoarray 50 by an objective lens 44.

Signals generated by chip 46 are conveyed by wires 32 to handle 24, andfrom there via a cable 38 (FIG. 1) to a video console, where the signalsare processed and used to drive a video display. The video console anddisplay (not shown in the figures) use standard video electronics, wellknown in the art. Alternatively, handle 24 may include a power source,such as one or more batteries, processing electronics and a videotransmitter, and convey processed signals from chip 46 to the videoconsole over a wireless link.

Lamps 42 preferably comprise white-light LEDs, such as T1 White L3-W31NLEDs produced by Sloan AG of Basel, Switzerland The lamps are powered byelectrical current conveyed over wires 32 and cable 38 from the console.Alternatively, the lamps may be powered by batteries in handle 24, asdescribed above. In either case, the use of lamps 42 alleviates thecomplication and expense of using a high-power fiberoptic light sourceto illuminate the area under view, as in endoscopes known in the art.

Window 36 is shown in FIG. 2 as being relatively small, in order tosimplify production and reduce the cost of sheath 26. Sheath 26 alsoincludes a transparent area surrounding the window to allow light fromlamps 42 to reach the area under view, but this area need not be ofoptical quality. In fact, all of sheath 26 may be made of transparentplastic if desired.

It will be observed that the optical axis of lens 44 and array 50 isangled obliquely relative to the longitudinal axis of member 28. Window36 and the distal end of sheath 26 are similarly angled. This anglingallows camera head 30 to view an area of the intestinal wall relativelynear the distal end of section 22, rather than pointing straight downthe intestine as in rigid rectoscopes and sigmoidoscopes known in theart. As a result of this arrangement, section 22 can be made relativelynarrow and pointed at its distal end, so that insertion through thesubject's anus is easier and less painful, without the need for aseparate obturator. Preferably, a bulbous projection 34 is formed at thedistal tip of sheath 26, shaped so as to penetrate the anus with aminimum of discomfort to the patient.

Sheath 26 preferably includes at least one working channel 38, whichterminates in an opening 52 at the distal end of the sheath. Channel 38may be used to inserted surgical tools, such as biopsy forceps, into theintestine and perform surgical procedures under view of camera head 30.The angled orientation of the camera head, as described above, isparticularly advantageous for viewing such procedures, since thesurgical tool will engage the intestinal wall within the camera head'sarea of view.

Additionally or alternatively, channel 38 may be used for suction,irrigation and/or insufflation of the intestine, by connecting thechannel to a suitable pump or gas source, as is known in the art.Preferably, the connection is made via handle 24, and the suction,irrigation or insufflation is controlled by user controls 40 on thehandle. Generally, it is desirable to insufflate the intestine duringexamination, so as to force the intestinal wall away from window 36 andthus provide camera head 30 with a clearer view of the wall. For thispurpose, sheath 26 preferably includes a one-way valve 54, such as aleaflet valve, as is known in the art, in channel 38. After apressurized gas has been passed through the channel to insufflate theintestine, valve 54 closes to prevent back-flow of the gas and maintainthe pressure in the intestine.

FIGS. 3A and 3B are schematic, sectional illustrations showing arectoscope 60 including a disposable sheath 62, in accordance withanother preferred embodiment of the present invention. Rectoscope 60includes a generally rigid insertion member 28 with a video camera head30 at its distal end, substantially as described above with reference toFIGS. 1 and 2, although in rectoscope 60, the optical axis of the camerahead is generally aligned with the longitudinal axis of member 28.

Sheath 62 comprises an outer layer 64 and an inner layer 66. The innerlayer preferably comprises a generally rigid plastic material, such aspolycarbonate, and fits snugly over member 28. Layer 66 includes atransparent distal portion, preferably including an optical window 68,as described above. Outer layer 64 is preferably made of a flexible,resilient plastic, such as polyethylene, and includes two or more leaves70, preferably three such leaves.

As shown in FIG. 3A, during insertion of rectoscope 60 through the anus,leaves 70 butt together, closing off the distal end of the rectoscopeand protecting window 68. The leaves preferably form a bluntly pointedstructure, which eases the insertion.

As shown in FIG. 3B, after the insertion, leaves 70 are opened to exposewindow 68 and allow camera head 30 to receive images of the interior ofthe intestine. Preferably, the leaves are opened by drawing outer layer64 in a proximal direction, out of the rectum (to the right in FIGS. 3Aand 3B), relative to inner layer 66. Each leaf 70 preferably includes aninner protrusion 72, which engages the surface of inner layer 66 andforces the leaf outward, as shown in the figure. After the rectoscopyprocedure is completed, sheath 62 may be returned to the configurationof FIG. 3A for removal through the anus.

FIG. 4A is a schematic, sectional illustration showing the distalportion of a rectoscope 76, in accordance with another preferredembodiment of the present invention. Rectoscope 76 is generally similarto rectoscope 20, shown in FIGS. 1 and 2, and comprises insertion member28 with camera head 30 at its distal end. Rectoscope 76 is covered by asheath 78, similar to sheath 26 except that sheath 78 includes a bulbousprotrusion 80 that extends into the field of view of camera head 30. Amirror 82 is fixed to protrusion 80, in such a position and orientationthereon that an image of a physiological structure 84, generally therectal wall, is reflected from the mirror, through window 36, and iscaptured by camera head 30. In the example shown in FIG. 4A, a surgicaltool 88 is inserted through working channel 38 in sheath 78 and is usedto take a biopsy sample at a point 86 on structure 84.

FIG. 4B is a schematic illustration showing a video image 90 capturedusing rectoscope 76 in the configuration of FIG. 4A. The upper part ofthe image shows tool 88 and structure 84 as seen by camera head 30directly through window 36. The image of the tool is foreshortened,because of the viewing angle of the camera head. It may therefore bedifficult to judge the distance from the tool to the structure based onsuch an image. An inset 92 in the lower portion of image 90 shows tool88 and structure 84 as seen via mirror 82. In this case, the angle fromwhich the tool is viewed allows its position and distance from structure84 to be seen clearly and controlled with greater accuracy.

FIG. 5A is a schematic, sectional illustration of the distal portion ofa rectoscope 106, in accordance with another preferred embodiment of thepresent invention. Rectoscope 106 is substantially similar to rectoscope20, shown in FIGS. 1 and 2, except that insertion member 28 ofrectoscope includes at least one flexible, resilient section 108.Section 108 preferably includes an elastic element, for example, aspring steel insert, which normally holds the section straight, butallows it to bend in response to lateral forces exerted thereon. Furtherpreferably, sheath 26 of rectoscope 106 includes flexible, elasticmaterial, for example, polyethylene or silicone, so that the sheath canbend and stretch accordingly when section 108 bends.

The ability of rectoscope 106 to bend allows it to be inserted into therectum, up to the sigmoid, more easily and with less pain and discomfortto the patient than a fully rigid rectoscope or sigmoidoscope wouldcause. Rigid endoscopes known in the art cannot have a flexible sectionlike rectoscope 106, since bending of the flexible section would disruptthe optical axis of the telescope that is used for endoscopic viewing.Although flexible sigmoidoscopes known in the art can be bent andinserted with less patient discomfort than rigid scopes, such flexiblescopes require complicated and costly steering mechanisms. By placingcamera head 30 at the distal end of rectoscope 106, the presentinvention allows a measure of flexibility without the necessity of asteering mechanism.

FIG. 5B is a schematic, sectional illustration showing a rectal insert102, for use in endoscopic examination and treatment of intestine 96 ofa patient, in accordance with a preferred embodiment of the presentinvention. Insert 102 is particularly useful for guiding rectoscope 106into the intestine, but may also be used in conjunction withconventional flexible endoscopes known in the art. Insert 102 ispreferably made of a generally rigid plastic material, such aspolycarbonate, but may be somewhat flexible so as to ease its insertion.The insert has a curved channel 104 passing therethrough, with an innerdiameter large enough for an endoscope, such as rectoscope 106, to beinserted through the channel.

Insert 102 is inserted through rectum 98 up to sigmoid flexure 100 ofintestine 96. The insert is turned so that channel 104 opens intosigmoid portion 101 of the intestine, as shown in FIG. 5B. Rectoscope106 is then passed through the insert and bends along the curve in thechannel. The distal end of the rectoscope, including camera head 30, ispushed out into sigmoid 101, allowing inspection and treatment of aportion of intestine 96 that would otherwise be accessible only using aconventional flexible endoscope. Insert 102 also protects the area offlexure 100 from pressure due to the rectoscope (or to a conventionalflexible endoscope inserted therethrough) that could otherwise causepain or even perforation of the intestine.

FIG. 6 is a schematic, sectional illustration showing a rectoscope 110,including a steering mechansim 111, in accordance with another preferredembodiment of the present invention. Rectoscope 110 comprises insertionmember 28 and camera head 30, covered by a disposable sheath 112 withoptical window 36 at a distal end thereof, as in other preferredembodiments described above. Member 28 of rectoscope 110 either has aflexible section, as described above with reference to FIG. 5A, or ismade flexible over substantially its entire length, as shown in FIG. 6.

Steering mechanism 111 comprises two flexible, elongate bladders 118 and120, contained within sheath 112 and disposed radially on opposing sidesof member 28. Bladders 118 and 120 have respective expandable wallsections 114 and 116, preferably accordion-type walls, as shown in FIG.6. The bladders are coupled via valves 124 to a pressure source 126, forexample, a gas bottle or pump, which may be contained either in a handle122 of rectoscope 110 or in a separate console. By operating valves 124,bladders 118 and 120 are pressurized to respective pressures P1 and P2.In the example shown in FIG. 6, P1 is greater than P2, causing wallsection 114 of bladder 118 to expand, and wall section 116 of bladder120 to contract, thereby causing member 28 to bend.

Mechanism 111 thus provides a simple, low cost, disposable means forcontrollably bending and steering rectoscope 110, by inflating anddeflating bladders 118 and 120 in sheath 112. Additional bladders may bepositioned along the length of the rectoscope and/or radially around itin order to give greater control of the bend shape and direction of therectoscope. It will be appreciated that such pressure-driven steeringmechanisms, either disposable or reusable, can also be applied toendoscopes of other types.

It will further be appreciated that the preferred embodiments describedabove are cited by way of example, and the full scope of the inventionis limited only by the claims.

1. A method for inserting an endoscope into the colon of a patient,comprising: providing a generally rigid insert having proximal anddistal ends and having a curved channel passing therethrough with alateral opening at the distal end; inserting the insert into thepatient's rectum so that the distal end is in proximity to the sigmoidflexure of the colon; rotating the insert to align the opening at thedistal end of the insert with the colon before passing the endoscopetherethrough; and passing the endoscope through the channel and into thesigmoid colon.
 2. A method according to claim 1, wherein passing theendoscope comprises passing a flexible endoscope through the channel. 3.A method according to claim 1, wherein passing the endoscope comprisespassing a generally rigid endoscope including a flexible portion throughthe channel, such that the flexible portion is bent by the curve of thechannel.